As a syringe for administering a small amount of a medical agent to a patient, a syringe having a piercing needle fixed to the distal end part of a barrel is used. In constructing a prefilled syringe in which the medical agent is filled in advance by using a syringe of this type, it is necessary to seal the tip of the syringe. Seal caps capable of sealing the tip of the syringe are proposed, as disclosed in a patent document 1 (Japanese Translation of PCT International Application Publication No. 2010-534546) and a patent document 2 (U.S. Pat. No. 6,719,732).
Prefilled syringes in which a medical agent has been filled in advance are used. But as apparent from a report that contents of many medical agents such as nitroglycerin, cyclosporine, benzodiazepines, and the like having a high degree of fat solubility decrease in various medical agent containers, interactions between injection solutions and medical appliances have become a problem. In consideration of this problem, as a material of a barrel for a syringe, resin such as cyclic polyolefin having a low degree of medicine adsorptive property has come to be used.
The present applicant proposed a prefilled syringe in which unlike the above-described needle-attached syringes, the barrel is sealed directly with the seal cap subjected to autoclave sterilization (Japanese Patent Application Laid-Open Publication No. 2005-319118: patent document 3).